Storm drains are typically covered by a grate, both for safety reasons and to prevent the entry of solid materials into sewers. Such a grating, however, allows the passage of smaller particulates into sewers. Standard storm drains therefore do not prevent the entry of environmentally hazardous materials, such as chemical liquids and plastic particulates, into sewer systems. In some cases, sewer lines carry such materials directly into the ocean or other natural bodies of water.
In order to better control the flow of materials into a sewer system, catch basins for use in sewer drains have been designed. For example, U.S. Pat. No. 7,052,207 to Wimberger discloses a catch basin having a drain tube covered with a filtration sock. U.S. Pat. No. 6,200,484 to McInnis discloses an alternative catch basin which makes use of a filter basket having openings sized to filter out solid debris from run-off water. Other catch basin designs are disclosed in U.S. Pat. Nos. 6,869,525; 6,093,314; and D501,672, and in U.S. Patent Publication No. 2005/0183997. There remains a need, however, for improved systems for filtering materials that pass through a sewer drain.